That hardly answers the question. Why does he think he'd be in so much more danger in Sweden? Why is being in the UK, where extradition is easy, better than being in Sweden, where extradition is hard?
Is Julian Assange really afraid of extradition? Personally, I think he's more afraid of indefinite detention in a Swedish government facility while being stuck in indefinite legal limbo.
In any case, does extradition even matter anymore? Sweden just went against common sense, against its own body of laws, and against existing precedents to redefine what a "rape" is supposed to be viewed like. Do you think that's just a coincidence? In my opinion, that's what Julian Assange should really be afraid of, the redefinition of law for his own "special" case and the prospect of being stuck indefinitely in a prison facility (where contact with the outside world is severely controlled and limited and your visitors are harassed and stripped-searched, assuming visitors are even allowed at all).
Why is being in Ecuador, where the CIA doesn't mind sending in assassins, better than being in Sweden?
Because the probability that the CIA will be successful in killing him in Ecuador is less than 100%, but should he return to Sweden, the probability that he will have to lose his freedom, be forced to stop most of his work, and be prosecuted under dubious just-made-up legal theory, is much closer to 100%.
It would have been terribly easy for the USA to extradite him directly from Britain.
Are you kidding me? If Assange was really extradited to the US. London would have a huge riot on its hands (and rightly so). And the current government would probably have to step down (or at least, make sure Assange never actually makes it on that plane, so that things can get back to normal without having the government needing to resign).
In any case, the extradition itself is a strawman. The threat of extradition and the legal limbo it creates, or the redefinition of "rape" and the legal limbo it creates, are more than enough to put Julian Assange under ice and out of commission for a number of years, even if none of those proceedings ever finally go through.